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No body is immune to impact by other bodies. Earth too is no stranger to body-play; Micro-micro meteorites accumulate by the giga-ton annually in the form of dust. Larger impact bodies such as the Chicxulub capable of delivering as much as 100 Teratons equivalent of TNT are also out there - but less frequent. As many as 132 meteorites found on Earth are identified as of Martian origin.

On October 17, 2013, NASA reported, based on analysis of argon in the Martian atmosphere by the Mars Curiosity rover, that certain meteorites found on Earth thought to be from Mars were actually from Mars.

Back in the 1960s/70s, Project Orion was a theoretical study on a nuclear pulse propelled space-ship. Several devices being flung out opposite to the desired direction of thrust. Each device imparting an absurdly humongous specific impulse on detonation.

What I therefore find myself wondering

  • How large would the impact have been on Mars to impart escape velocity to the rocks that eventually turned up on Earth?

  • Even given the turbulent environment on Mars, is there a possibility one of the impact craters - the source of an eventual martian meteorite, may be discovered by one of the missions presently on/under-way to Mars?

  • Is there a probability of discovering a Venerean meteorite here on Earth?

  • Could Chicxulub, or a comparable impact have imparted escape velocity, or larger to a rock such that it would eventually wind up on Mars, or Venus?

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    $\begingroup$ Come on people, at-least leave a remark when you down-vote $\endgroup$ – Everyone Jun 9 '14 at 17:58
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    $\begingroup$ I'm not sure how Project Orion is relevant to your question. $\endgroup$ – Keith Thompson Jun 9 '14 at 20:16
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    $\begingroup$ @KeithThompson: I linked Prj.Orion for reference to the device yield as compared to a large impact meteor such as Chicxulub $\endgroup$ – Everyone Jun 10 '14 at 1:27
  • $\begingroup$ Everyone knows that some answers to this question suggest nuclear explosions can't put rocks into escape velocity, so Everyone includes a counterexample to this thinking in the question. Explosions can in sone situations propel stuff. $\endgroup$ – uhoh Oct 29 '16 at 0:19
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There should be. It needs a huge impact on Earth to send material all the way to Mars but we get them occasionally. You need something of the order of the Chicxulub impact 66 million years ago. The debris would take about a hundred years, for the first material to get there and the material would continue to arrive on Mars for up to 20 million years from that date. So probably the youngest meteorite from Earth would be over 40 million years old.

Though you didn't ask it, but to follow up on the other answers, it is very hard to get meteorites from Venus to Earth. The problem is the thick atmosphere. An impact like the Chicxulub impact would send meteorites to Earth if its atmosphere was similar to Earth's. But with its thick atmosphere, it would need to be much larger. And from the impact history on the Moon, Mercury and Mars then the larger 100 km scale impacts all date back to well over 3 billion years ago.

However way back then, then Venus might also have had a thin atmosphere. So there could be Venusian material on Earth, a bit of it, but it would be impossible to recognize after all that time and weathering. But if this is right, then it's probably there on the Moon, and much easier to spot as it wouldn't be weathered, and there might be Venusian meteorites on Mars.

There could also be Mercurian meteorites on Earth - and Mars also. Mercurian Impact Ejecta: Meteorites and Mantle

I think the best place to look for Earth meteorites is on the Moon. If they landed in frozen areas of the Moon, they may preserve organics from millions or even billions of years. They could also preserve fossils as fossil diatoms are still recognizable, and the smallest ones intact after a simulated impact on the Moon. There may be as much as 200 kilograms of material from Earth per square kilometer of the lunar surface. Details see my Record keeper of inner solar system (including astrobiology and early life on Earth)

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The majority of the rocks from Mars appear to have come from a single impact on Mars, which formed Mojave Crater. I'm finding it difficult to get an exact power for that impact, but the crater is 58 km in diameter. It is a very large crater, one of the type that rarely impacts anywhere.

Discovering a Veneran meteorite would be quite rate, as LocalFluff mentioned. It's not impossible, but it would have to be the result of a very large impact, which seems unlikely. It is likely there is rocks from Venus around, just that they are likely buried after a long time in the past.

It certainly is possible that a rock from Earth could have made it to Mars, but that isn't all that likely. Most likely, any such rock would be from the Late Bombardment period, as that's the only time in Earth's history with such power, at least, with Earth as we know it. I have little doubt that the impact that resulted in the Moon showed the solar system, however, it is unlikely that many of those fragments have continued to survive, except perhaps in deep space.

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    $\begingroup$ Late bombardment? You are forgetting about Theia. $\endgroup$ – David Hammen Jun 10 '14 at 0:42
  • $\begingroup$ I meant that would have recorded life. It's true that the Moon essentially is one big rock, and no doubt there are piece of the Earth from that collision everywhere in the solar system, but... $\endgroup$ – PearsonArtPhoto Jun 10 '14 at 1:15
  • $\begingroup$ @DavidHammen Do we actually have any evidence that collisions between larger celestials results in a large number of debris? I would imagine that at such energy, most if not all the mass involved liquefies even before the impact's kinetic transfer and cohesive and adhesive forces prevent large number of smaller debris scattering around? I.e. the whole mass would behave more like a collision between molten rock, than rock fragments? (p.s. it's a speculation, I have no clue if that's true at all) $\endgroup$ – TildalWave Jun 10 '14 at 12:41
  • $\begingroup$ @TildalWave: We have the Moon, I think that's a pretty big piece of evidence. $\endgroup$ – PearsonArtPhoto Jun 10 '14 at 12:42
  • $\begingroup$ @PearsonArtPhoto That's two pieces :) ... I meant a large number of fragments. I can see this coming down to fluid dynamics more than hard body collisions (when it comes to momentum transfer and acceleration of individual pieces beyond escape velocity in all directions). I.e. I can see how they could be a product of impact shock wave(s) like when you collide two liquid bodies, but I fail to imagine something that would resemble an impact of two sandbags, with any number of particles moving independently away from the impact site. $\endgroup$ – TildalWave Jun 10 '14 at 12:46
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- Is there a probability of discovering a Venerean meteorite here on Earth?

Possible but unlikely. No (known) venerean meteorite has been found on Earth. Several factors make it much more unlikely than a meteorite from Mars (I should write "much less common", certainly some are around, but so few that we might never find them). Venus' deeper gravity well and shorter distance to the Sun turn meteoroids away from Earth orbit. And the thick atmosphere of Venus slows down ejecta.

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  • $\begingroup$ Accepted Venus' deeper gravity well may turn meteoroids away from Earth orbit. The thick atmosphere though shouldn't be relevant once ejecta achieve adequate velocity ... albeit to be fair, the thick atmosphere may serve to rob the velocity of even extremely large impact objects. $\endgroup$ – Everyone Jun 9 '14 at 17:57
  • $\begingroup$ @Everyone About the atmosphere, to whatever degree it matters, maybe in the past Venus had a much thinner atmosphere. And Mars is believed to have had much thicker atmosphere early on when most of the bombardments happened. $\endgroup$ – LocalFluff Oct 29 '16 at 10:10

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